Negative differential conductance effect and electrical anisotropy of 2D ZrB2 monolayers

TL;DR

This study reveals that 2D ZrB2 monolayers exhibit electrical anisotropy and negative differential conductance, with potential applications in nanoscale electronic devices, as shown through theoretical calculations of their transport properties.

Contribution

It is the first detailed theoretical analysis of the electrical transport and NDC effect in 2D ZrB2 monolayers along different crystallographic directions.

Findings

Electrical transport is similar along zigzag and armchair directions at low bias.

High bias induces electrical anisotropy and divergence in I-V curves.

Both ZrB2 orientations exhibit negative differential conductance.

Abstract

Two-dimensional (2D) metal-diboride ZrB2 monolayers was predicted theoretically as a stable new electronic material [A. Lopez-Bezanilla, Phys. Rev. Mater., 2018, 2, 011002 (R)]. Here, we investigate its electronic transport properties along the zigzag (z-ZrB2) and armchair (a-ZrB2) directions, using the density functional theory and non-equilibrium Green's function methods. Under low biases, the 2D ZrB2 shows a similar electrical transport along zigzag and armchair directions as electric current propagates mostly via the metallic Zr-Zr bonds. However, it shows an electrical anistropy under high biases, and its I-V curves along zigzag and armchair directions diverge as the bias voltage is higher than 1.4 V, as more directional B-B transmission channels are opened. Importantly, both z-ZrB2 and a-ZrB2 show a pronounced negative differential conductance (NDC) effect and hence they can be promising for the use in NDC-based nanodevices.